Entrepreneurs used to show nice Excel spreadsheets to their potential investors. Sales were nicely going up and investors were often doubtful about how it would actually take off. Before coming up with a business plan, you'd rather think twice about how to create some traction.
And this might change the whole business plan. It will take a few months to show some early traction, but this is worth it. Investors will prefer that to a blank sheet of paper with a bright idea and nothing achieved yet
Here are a few things that will show traction:
try to get a first MVP - minimum viable product - find out for a low cost solution that could still show some nice features and prove the value of your idea,
get an initial mark of interest from a potential client - that is the ideal traction - if you don't have it yet, at least show at what stage of the discussions you are,
build your team with talents that will suppement each other and reassure the investors - people might not be officially working for you already but they are committed, working behind the scene and ready to jump in when there will be financing,
initiate partnerships, even if your product or application is not ready yet does not mean you cannot do some initial partnership and marketing work with others,
even if getting press articles and testimonials does not mean customers want your product, this does not hurt
Once you have the plan set up to get some traction, then it is time to start building your business plan.